Previously, it has been performed that a hard film containing Ti or Al is coated on a surface of a tool, thereby improving wear resistance of the tool. For example, Patent Document 1 discloses a technique of forming a metal-containing hard film as the above-mentioned hard film in atmosphere gas comprising a carbon-containing gas and a rare gas as main components by an arc method. However, in the method of Patent Document 1, only hydrocarbon gas is used as reaction gas, and the metal-containing hard film formed is a carbide film containing only carbon as a non-metallic component. The carbide film shows a low friction coefficient, but has a defect of insufficient wear resistance.
On the other hand, a nitride film containing at least any one element of Ti, Cr and Al has a high hardness and also has excellent oxidation resistance, so that it has been coated on a surface of a cutting tool, a die or a machine component and has been used as a wear-resistant film. However, the above-mentioned nitride film has high friction coefficients with respect to various materials, so that it has a disadvantage of easy occurrence of baking in a sliding environment.